Koo Kien Keat (simplified Chinese: 古健杰; traditional Chinese: 古健傑; pinyin: Gǔ Jiànjié; Peh-ōe-jī: Kóo Kiān-kiat; born September 18, 1985 in Ipoh, Perak) is a professional badminton player from Malaysia. Besides being a men's doubles player, he also represents Malaysia in the mixed doubles event. He started his career at seventeen years of age and has won the Asian Junior title. He played in the Thomas Cup 2004 with Chan Chong Ming. They won bronze in the World Championship 2005. His current doubles partner is Tan Boon Heong, and together, in 2010, they became the number 1 ranked men's doubles team in the world. They have since lost that ranking but remain one of the top men's doubles team in the world.